4th Grade Factors, Multiples, Prime and Composite Worksheet Solutions (PDF)

4th Grade math worksheet solutions: Factors, Multiples, Prime and Composite – Maths PDF

Cover of the book Grade 4 Math Worksheets with Answers (PDF)

Download as a PDFThe Grade 4 worksheets book with answersPrintable PDFSee the book ›

Sommaire

This factors multiples answers for 4th Grade covers factors, multiples, prime and composite (Common Core 4.OA.B.4), with a free PDF to print.

Use this answer key to check each solution on the factors and multiples worksheet. Every problem shows the factor pairs or the skip counting used, so students can find any mistake and fix it.

Grade 4 · Common Core State Standards: 4.OA.B.4

Factors multiples answers: exercises 1 to 10

Exercise 1 – Factor pairs of 12

Try each number from 1 up: \(1 \times 12 = 12\), \(2 \times 6 = 12\), \(3 \times 4 = 12\). Next, 4 is already used, so stop.

Factor pairs: 1 and 12, 2 and 6, 3 and 4.

Exercise 2 – Factors of 18

Pairs: \(1 \times 18\), \(2 \times 9\), \(3 \times 6\). 4 and 5 do not divide 18 evenly, and 6 is already listed.

Factors: 1, 2, 3, 6, 9, 18.

Exercise 3 – Multiples of 7

Skip count by 7: 7, 14, 21, 28, 35, 42.

Check: \(7 \times 6 = 42\). The multiples are 7, 14, 21, 28, 35, 42.

Exercise 4 – Reading an array

There are 5 rows of 6 tiles: \(5 \times 6 = 30\).

Factor pairs of 30: \(1 \times 30\), \(2 \times 15\), \(3 \times 10\), \(5 \times 6\).

Two of the four arrays that make 30.

Answer: \(5 \times 6 = 30\); pairs 1 and 30, 2 and 15, 3 and 10, 5 and 6.

Exercise 5 – Is it a factor?

Divide: \(54 \div 6 = 9\) with no remainder, or \(6 \times 9 = 54\).

Yes, 6 is a factor of 54.

Exercise 6 – Is it a multiple?

(a) \(8 \times 7 = 56\), so 56 is a multiple of 8.

(b) \(8 \times 7 = 56\) and \(8 \times 8 = 64\), so 58 falls between two multiples.

Answer: (a) yes, (b) no.

Exercise 7 – Multiples of 4 in a list

Check each: \(4 \times 5 = 20\), \(4 \times 8 = 32\), \(4 \times 11 = 44\). The numbers 14, 26 and 38 leave a remainder of 2 when divided by 4.

Multiples of 4: 20, 32, 44.

Exercise 8 – Missing multiples

Each jump is 8. After 16 comes \(16 + 8 = 24\). After 32 comes \(32 + 8 = 40\). After 56 comes \(56 + 8 = 64\).

All ten multiples of 8 up to 80.

Missing numbers: 24, 40, 64.

Exercise 9 – Prime or composite

7 has factors 1 and 7 only: prime. 9 has factors 1, 3, 9: composite. 11 has factors 1 and 11 only: prime. 15 has factors 1, 3, 5, 15: composite.

Answer: 7 prime, 9 composite, 11 prime, 15 composite.

Exercise 10 – Primes from 20 to 40

Remove the even numbers and the multiples of 5. Then test the rest: 21 = \(3 \times 7,\) 27 = \(3 \times 9,\) 33 = \(3 \times 11,\) 39 = \(3 \times 13\) are composite. 25 is a multiple of 5.

What is left: 23, 29, 31, 37.

Primes: 23, 29, 31, 37.

Exercises 11 and up

Exercise 11 – Odd one out

Test each number for a factor other than 1 and itself. 13 and 17 and 23 have no other factors. For 21, try 3: \(3 \times 7 = 21\).

So 21 has the factors 1, 3, 7 and 21, which is more than two.

Answer: 21 is not prime, because \(3 \times 7 = 21\).

Exercise 12 – Divisibility by last digit

The last digit is 5.

(a) 5 is not 0, 2, 4, 6 or 8, so not divisible by 2.

(b) The last digit is 5, so divisible by 5.

Answer: (a) no, (b) yes, (c) no.

Exercise 13 – Factor pairs of 36

\(1 \times 36\), \(2 \times 18\), \(3 \times 12\), \(4 \times 9\), \(6 \times 6\). The factor 6 is counted once.

Factor rainbow for 36.

Factors: 1, 2, 3, 4, 6, 9, 12, 18, 36. Answer: 5 factor pairs, 9 factors.

Exercise 14 – Factors of 48

Pairs: \(1 \times 48\), \(2 \times 24\), \(3 \times 16\), \(4 \times 12\), \(6 \times 8\). 5 and 7 do not divide 48.

Factors: 1, 2, 3, 4, 6, 8, 12, 16, 24, 48 (10 factors).

Exercise 15 – Sticker poster

Row lengths are the factors of 28. Pairs: \(1 \times 28\), \(2 \times 14\), \(4 \times 7\). (5 and 3 do not work.)

Three arrays, each with 28 stickers.

Row lengths: 1, 2, 4, 7, 14, 28.

Exercise 16 – Muffin boxes

The totals must be multiples of 6. \(6 \times 7 = 42\) and \(6 \times 9 = 54\). For 50: \(6 \times 8 = 48\), remainder 2. For 62: \(6 \times 10 = 60\), remainder 2.

Answer: 42 and 54.

Exercise 17 – Team sizes

Team sizes must be factors of 30: 1, 2, 3, 5, 6, 10, 15, 30.

Keep sizes from 2 to 10: 2, 3, 5, 6, 10.

Answer: 2, 3, 5, 6 or 10 players per team.

Exercise 18 – Bus schedule

Add 15 minutes each time. After 8:45 come 9:00, 9:15 and 9:30.

9:30 AM is 90 minutes after 8:00, and \(15 \times 6 = 90\), so it is a multiple of 15.

Answer: 9:00, 9:15, 9:30; yes, a bus leaves at 9:30.

Exercise 19 – Mystery prime

Primes between 40 and 50: 41, 43, 47 (42, 44, 46, 48, 50 are even, 45 is a multiple of 5, 49 = \(7 \times 7\)).

Digit sums: 4 + 1 = 5, 4 + 3 = 7, 4 + 7 = 11.

Answer: 47.

Exercise 20 – Ethan's claim

Try 3: \(3 \times 17 = 51\). So 51 has the factors 1, 3, 17 and 51.

A prime number has only two factors, so 51 is composite.

Answer: No. 51 = \(3 \times 17,\) so it is composite.

Key facts behind this factors multiples answers

Key facts

A factor pair multiplies to make the number, such as 3 and 8 for 24.
A number has a limited list of factors but endless multiples.
A prime number has exactly two factors; a composite number has more than two.
The number 1 is neither prime nor composite, and 2 is the only even prime.
Last-digit patterns: 2 for even numbers, 5 for 0 or 5, 10 for 0.

How to use this factors multiples answers

Cover each solution, solve the exercise again, then uncover it and compare every line. If your answer differs, find the first step that changed and redo the exercise from there.

Download the factors multiples answers as a PDF with the button below and keep it with your notes.

All Grade 4 chapters: Grade 4 math.

Voter.. post

Free printable PDF